The most usual method of providing a "stone-washed" look (localized abrasion of the colour) in denim fabric or jeans is by washing the denim or jeans made from such fabric in the presence of pumice stones to provide the desired localized lightening of the colour of the fabric. Using pumice for this purpose has the disadvantage that pumice particles have to be washed from the fabric or clothing subsequently to treatment, and that the pumice stones and particles cause a significant wear of the machines used in the process. Also, handling large amounts of stones may be a problem.
Other approaches to providing a "stone-washed" appearance to denim fabric or jeans have therefore been suggested. For instance, enzymes, in particular cellulolytic enzymes, have been suggested for this purpose, either alone (U.S. Pat. No. 4,832,864) or together with a smaller amount of pumice than required in the traditional process.
It has been suggested that it may be advantageous to substitute pumice with perlite, especially heat expanded perlite, in the stonewashing process. Since perlite has a considerably lower density than pumice, this substitution may reduce the mentioned disadvantages of using pumice.
However, it has turned out that the desired "stonewashed" look of dyed fabric can not be obtained by using perlite instead of pumice stones in the conventional stonewashing process, i.e. by treating ("stone-washing") the fabric in the presence of perlite.
Perlite may be a dusting material and especially the handling thereof when carrying out the "stone-washing" process may create dust which is unpleasant and annoying to the personnel and even dangerous to their health, and, furthermore, requires frequent cleaning of the process area.
Thus, there is still a need for an improved method of providing a stone-washed look in dyed fabric which eliminates the handling problems of the known methods while at the same time being cost-efficient as well as for an improved composition for the treatment of dyed fabric.